Carburetor

ABSTRACT

NO O.G. CLAIM/ABSTRACT AVAILABLE IN IFI DATABASE FOR THIS PATENT

Nov. 26, g@ J. w. MOULDS LZl CARBURETOR Filed July 2e, 1973 United States Patent 3,851,021 CARBURE'IUR .lohn W. Moulds, Fairfield, N .Y., assigner to General Motors Corporation, Detroit, Mich. Filed July 26, 1973, Ser. No. 382,685 lint. Cl. FllZm 7/22 US. Cl. 261-50 A 4 Claims ABSTRACT F THE DESCLUSURE In an air valve carburetor, the metering rod hanger is received and retained in a socket formed in the metering rod.

This invention relates to an internal combustion engine carburetor and more particularly to a carburetor in which the metering rod is operated by a hanger received and retained in a socket formed in the base of the metering rod. The construction provided by this invention may be more easily assembled during production and repair operations than prior constructions and yet prevents accidental uncoupling during engine operation.

The details as well as other objects and advantages of this invention are set forth in the remainder of the speciiication and are shown in the drawings in which:

FIG. 1 is a sectional elevational View of the carburetor showing the basic metering linkage;

FIGS. 2 and 3 are enlarged views of the metering rod showing the configuration of the tapered metering portion; and

FIG. 4 is an enlarged view of the hanger-metering rod interconnection.

Referring first to FIG. l, the carburetor 19 has a mixture conduit 12 including an air inlet 1d and a mixture outlet 16 which discharges to the engine. A throttle 18 is disposed in mixture outlet 16 in the usual manner on a throttle shaft 20.

An air valve 22 is disposed in air inlet 14 on an air valve shaft 24. A spring 26 is secured to the downstream edge 28 of air valve 22 and extends to a bracket 3l) to bias air valve 22 to the position shown.

A tang 32 reaches upwardly from air valve 22 and is connected by a link 34 to a diaphragm 36. A chamber 38, formed between the right side of diaphragm 36 and a cover member 40, is connected by a tube 42 to a region 44 of mixture conduit 12 defined between air valve 22 and throttle 18.

A chamber 46, defined between the left side of diaphragm 36 and a cover member 48, is subjected to substantially atmospheric pressure, present in air inlet 14 and in the air cleaner (not shown), through openings such as 50, 52 and S4. (The air cleaner seats on a rim 56 disposed about the upper portion of carburetor 10.)

In operation, chamber 38 is subjected to the subatmospheric pressure created in region 44 as throttle 18 is opened, and diaphragm 36 acts through link 34 to pull air valve 22 clockwise to an open position. Spring 26 is eective to balance the opening force of diaphragm 36, thereby creating a substantially constant subatmospheric pressure in region 44. By thus establishing a generally constant pressure drop across air valve 22, the area about air valve 22 and thus the rotative position of air valve 22 is determined by and is a measure of the rate of air flow through mixture conduit 12.

A tab 58 extends upwardly from air valve 22 and is connected through a link 66 to one end 62 of a lever 64. The opposite end 66 of lever 64 is pivoted about a pin 68. Intermediate ends 62 and 66, a hanger 70 extends from lever 64 into the carburetor fuel bowl 72. The lower end 74 of hanger 70 has a hook 76 which is received in a socket 78 formed in the lower end of a metering rod 8l).

ICC

It may be noted that hanger 7l) extends through an opening 82 in the cover 84 for fuel bowl 72. Opening 82 is closed by a slider 86 which shifts horizontally during movement of hanger 70.

Metering rod 80 is disposed in a fuel passage 88 having its lower end 90 disposed to receive fuel from a well 92 formed in the bottom of fuel bowl 72. The upper end 94 of fuel passage 38 has an opening 96 through which fuel is discharged into region 44 of mixture conduit 12. It will be appreciated, therefore, that the fuel in fuel bowl 72 is subjected to a substantially constant metering headfrom the substantially atmospheric pressure in the upper portion of the fuel bowl to the generally constant pressure in region 44.

A metering jet or orifice 98 is disposed in fuel passage 8S around the tip 99 of metering rod 80. As best shown in FIGS. 2 and 3, metering rod Sil has flat tapered surfaces ltltl on opposite sides which, upon reciprocation of metering rod 80 in jet 98, varies the area available for fuel flow through jet 98.

In operation, as air valve 22 opens by clockwise rotation, link rotates lever 64 in a clockwise direction. Lever 64 then lifts hanger 76 to move metering rod Si) generally upwardly and rightwardly in fuel passage S8. Thus as air valve 22 is opened to increase the area available for air flow through air inlet 14, metering rod 0 is shifted to increase the area available for fuel flow through metering orifice 98. By this means, a substantially constant air-fuel ratio may be maintained-the precise proportion being controlled by the geometry of tapered surfaces lll() and of the linkage between air valve 22 and metering rod Sil.

A spring 102 extends from an annular ledge "rtl4 formed in fuel passage 88 to the lower end 1l6 of metering rod to take up any slack in the linkage and to load metering rod Si) against jet 9%.

It may be noted from FIG. 3 that the thickness of metering rod 8) increases from the end of surfaces llltl most closely adjacent passage inlet to tip 99. Tip 99 is therefore enlarged and assists in discharging fuel from fuel passage 88 as air valve 22 and metering rod 8d are moved to increase air and fuel flow. This offsets the greater inertia of the fuel which otherwise could create a mixture temporarily leaner than desired.

Referring now to FIG. 4, it may be observed that socket 7 it comprises an elongated cylindrical recess or cavity 168 having a conical bearing surface at its upper end and that a window 112 opens laterally into the lower end of cavity 108. The hooked portion 76 at the lower end 74 of hanger 70 extends through window 112 and has a spherical tip 114 received by conical surface 116 of socket 78. Spherical tip 114 engages conical surface 110 along a circular line which may translate slightly over tip 114- and surface 110 as the orientation. of hanger 7d relative to metering rod 80 varies during operation.

While metering rod 30 could be. secured to 'hanger "ill by the conventional method of wrapping a wire about both metering rod 8l) and hanger 70, the extra material and labor required by such a method is avoided by the construction shown in FIG. 4. Here the lower edge of window 112 is defined by a bar 116 extending below lower end 74 of hanger 7l?. Assembly and intentional disassembly of metering rod 80 and hanger 7l) is permitted by pivoting hooked portion 76 through window 112, and rotation of hanger 71B relative to meterin .g rod 30 (about tip 114) is permitted by the length of window 112. However, accidental uncoupling of metering rod 8G from hanger 'i'll during engine operation is prevented by bar 116 which precludes axial motion of metering rod 80 relative to hanger 70 suliicient to dislodge hooked portion 76 from socket 78.

It is apparent from the foregoing that this invention provides a metering rod and hanger construction which is easily assembled and disassembled for manufacture and repair and yet which is prevented from accidentally uncoupling during engine operation.

The embodiments of the invention in which an exclusive property or privilege is claimed are dened as follows:

l. A carburetor comprising a mixture conduit, a fuel bowl, a fuel passage having an inlet receiving fuel from said fuel bowl and an outlet discharging fuel into said mixture conduit and extending upwardly from said inlet to said outlet, a metering orifice disposed in said fuel passage, a metering rod reciprocably disposed in said passage inlet, said metering rod having a portion disposed in said orifice for controlling fuel flow from said fuel bowl through said passage and said orifice to said mixture conduit, said metering rod having an axially extending cavity formed in its lower end and a window opening laterally into the lower end of said cavity, and a hanger disposed generally vertically in said fuel bowl and having a hooked portion at its lower end, said hooked portion being received through said window and extending into the upper portion of said cavity and supporting said metering rod for reciprocation within said fuel passage, said 4metering rod further having means defining a lower edge of said window to prevent accidental uncoupling of said metering rod from said hanger.

2. A carburetor comprising a mixture conduit, a fuel bowl, a fuel passage having an inlet receiving fuel from said fuel bowl and an outlet discharging fuel into said mixture conduit and extending upwardly from said inlet to said outlet, a metering orifice disposed in said fuel passage, a metering rod reciprocably disposed in said passage inlet, said metering rod having a portion disposed in said orifice for controlling fuel iiow from said fuel bowl through said passage and said orice to said mixture conduit, said metering rod having an elongated cylinrical recess extending into its lower end and a window opening laterally into the lower end of said recess7 and a hanger disposed generally vertically in said fuel bowl and having a hooked portion -at its lower end, said hooked portion being received through said window and extending into the upper portion of said recess and supporting said rnetering rod for reciprocation within said fuel passage, said metering rod further having a bar extending across and defining a lower edge of said window to prevent accidental uncoupling of said metering rod from said hanger.

3. A carburetor comprising a mixture conduit, a fuel bowl, a fuel passage having an inlet receiving fuel from said fuel bowl and an Outlet discharging fuel into said mixture conduit and extending upwardly from said inlet to said outlet, a metering orifice disposed in said fuel passage, a metering rod reciprocably disposed in said passage inlet, said metering rod having a portion disposed in said orifice for controlling fuel flow from said fuel bowl Cil through said passage and said orice to said mixture conduit, said metering rod having an elongated cylindrical recess extending into its lower end and a window opening laterally into the lower end of said recess, and a hanger disposed generally vertically in said fuel bowl and having a hooked portion at its lower lend, said hooked portion being received through said window and extending into the upper portion of said recess and supporting said metering rod for reciprocation within said fuel passage, said upper portion of said recess being formed to define a conical surface and said hooked portion of said hanger terminating in a spherical surface received by said conical surface whereby the line of contact between said surfaces may translate during relative movement of said hanger and said metering rod.

4. A carburetor comprising a mixture conduit, a fuel bowl, a fuel passage having an inlet receiving fuel from said fuel bowl and an outlet discharging fuel into said mixture conduit and extending upwardly from said inlet to said outlet, a metering orifice disposed in said fuel passage, a metering rod reciprocably disposed in said passage inlet, said metering rod having a portion disposed in said orice for controlling fuel flow from said fuel bowl through said passage and said orifice to said mixture conduit, said metering rod having an elongated cylindrical recess extending into its lower end and a window opening laterally into the lower end of said recess, and a hanger disposed generally vertically in said fuel bowl and having a hooked portion at its lower end, said hooked portion being received through said window and extending into the upper portion of said recess and supporting said metering rod for reciprocation Within said fuel passage, said upper portion of said recess being formed to define a conical surface and said hooked portion of said hanger terminating in a spherical surface received by said conical surface whereby the line of contact between said surfaces may translate during relative movement of said hanger and said metering rod, said metering rod further having a bar extending across and delining a lower edge of said window to prevent accidental uncoupling of said metering rod from said hanger.

References Cited 

